Genetic variation in HTLV-III/LAV over time in patients with AIDS or at risk for AIDS

In a study of genetic variation in the AIDS virus, HTLV-III/LAV, sequential virus isolates from persistently infected individuals were examined by Southern blot genomic analysis, molecular cloning, and nucleotide sequencing. Four to six virus isolates were obtained from each of three individuals over a 1-year or 2-year period. Changes were detected throughout the viral genomes and consisted of isolated and clustered nucleotide point mutations as well as short deletions or insertions. Results from genomic restriction mapping and nucleotide sequence comparisons indicated that viruses isolated sequentially had evolved in parallel from a common progenitor virus. The rate of evolution of HTLV-III/LAV was estimated to be at least 10(-3) nucleotide substitutions per site per year for the env gene and 10(-4) for the gag gene, values a millionfold greater than for most DNA genomes. Despite this relatively rapid rate of sequence divergence, virus isolates from any one patient were all much more related to each other than to viruses from other individuals. In view of the substantial heterogeneity among most independent HTLV-III/LAV isolates, the repeated isolation from a given individual of only highly related viruses raises the possibility that some type of interference mechanism may prevent simultaneous infection by more than one major genotypic form of the virus.     

Type-restricted neutralization of molecular clones of human immunodeficiency virus

In a study of the immunologic significance of the genetic diversity present within single isolates of human immunodeficiency virus type 1 (HIV-1), the neutralization of viruses derived from molecular clones of the HIV-1 strain HTLV-IIIB by an extensive panel of sera was compared. Sera from HIV-1-infected patients and from goats immunized with polyacrylamide gel-purified HIV-1 envelope glycoprotein (gp120), native gp120, or gp120-derived recombinant peptides, showed marked heterogeneity in neutralizing activity against these closely related viruses. The change of a single amino acid residue in gp120 may account for such "clonal restriction" of neutralizing activity.     

Evaluation of a regimen using a progesterone releasing intravaginal device (CIDR) and PMSG as a treatment for post partum anoestrus in dairy cattle

Anoestrous dairy cows in seasonally calving herds in the Macalister Irrigation District of Gippsland, Victoria were treated at the start of the mating period with a progesterone releasing intravaginal device (CIDR). The CIDR was inserted for 7 days and 400 IU of PMSG was injected intramuscularly at removal. There was no clinically useful difference among cows receiving the CIDR, a placebo and untreated cows in the interval from treatment to either first oestrus or conception, the conception rate to first service or percent pregnant by the end of mating. Analyses of data from 2-year-old cows, older cattle, cows calved at least 45 days or cows calved at least 55 days and cows treated 3 weeks after the start of mating did not show improved reproductive performance following treatment with the CIDR.     

Absence of detectable arsenate in DNA from arsenate-grown GFAJ-1 cells

A strain of Halomonas bacteria, GFAJ-1, has been claimed to be able to use arsenate as a nutrient when phosphate is limiting and to specifically incorporate arsenic into its DNA in place of phosphorus. However, we have found that arsenate does not contribute to growth of GFAJ-1 when phosphate is limiting and that DNA purified from cells grown with limiting phosphate and abundant arsenate does not exhibit the spontaneous hydrolysis expected of arsenate ester bonds. Furthermore, mass spectrometry showed that this DNA contains only trace amounts of free arsenate and no detectable covalently bound arsenate.     

Survival and fertility after uterine prolapse in dairy cows

Sixty-eight cases of uterine prolapase in pastured dairy cows were treated in 2 consecutive spring calving seasons in East Gippsland, Victoria. Fifty cows survived (73.5%). Of 43 cows available for followup, 36 (84%) conceived in the mating period following the prolapse, taking 10 d longer to conceive than herd mates that calved on the same day. Three of the 36 cows (8%) that conceived, aborted, this occurring in the middle trimester of pregnancy. No prolapses occurred at the following calving but one case had suffered uterine prolapse 2 years previously. The conclusions drawn from these observations are that cows with uterine prolapse have a good chance of surviving if treated, that treatment is cost-effective, that uterine prolapse is unlikely to reoccur and treated cows have a good chance of conceiving. The veterinarians involved in this investigation were reasonably accurate in their ability to predict long term survival but not as good in predicting ability to conceive again.